https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91599
Bug ID: 91599
Summary: GCC does not say where warning is happening
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: sje at gcc dot gnu.org
Target Milestone: ---
When compiling the following source file, GCC gives a warning. The warning
notes that the declaration is on line 2 but it does not say what line the
actual write is on (line 12). This message started showing up with Martin
Sebor's patch for PR c++/83431 though I don't know if he added it or if he just
made it show up in places where it wasn't happening before.
% cat x.c
struct charseq {
unsigned char bytes[0];
};
struct locale_ctype_t {
struct charseq *mboutdigits[10];
};
void ctype_finish (struct locale_ctype_t *ctype)
{
long unsigned int cnt;
for (cnt = 0; cnt < 20; ++cnt) {
static struct charseq replace[2];
replace[0].bytes[1] = '\0';
ctype->mboutdigits[cnt] = &replace[0];
}
}
% install/bin/gcc -O2 -c x.c
x.c: In function ‘ctype_finish’:
cc1: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=]
x.c:2:18: note: destination object declared here
2 | unsigned char bytes[0];
|
It would be nice if the warning said the write was on line 12 as well as saying
that the declaration is on line 2. This test case is cutdown from code in
glibc where the code doing the write was less easy to find.
